<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>VueDemo2</title>
    <script src="js/vue.js"></script>
    <script>
        window.onload = function () {
            Vue.config.devtools = false;
            Vue.config.productionTip = false;
            var vm = new Vue({
                el: "#app",
                data: {
                    msg: ""
                }
            })
        }
    </script>
</head>

<body>
    <div id="app">
        <input type="text" v-model="msg">
        <br>
        <span v-text="msg"></span>
    </div>
</body>

</html>